In the art of security printing, in particular the printing of banknotes or similar printed securities, the printed documents are commonly numbered at the end of the printing process, each document receiving a unique combination of alphanumeric characters and/or symbols which builds the so-called serial number of the security document.
Numbering is commonly performed at a stage of the printing and processing process where the sheets or webs onto which the securities are printed have not yet been cut into individual security documents. At this stage, security prints which are ultimately intended to form the security documents are arranged on the substrate in columns and rows, forming an array with a predetermined number of security prints. These printed substrates, which can either take the form of individual sheets or repetitive lengths of a continuous web, are passed through a numbering machine where the serial numbers are applied to each security print on the substrate. Numbering processes and devices for carrying out these numbering processes are for instance disclosed in German Patent DE 25 02 987 (corresponding to U.S. Pat. No. 3,939,621 and U.S. Pat. No. 4,045,944), German Patent DE 26 34 221 (corresponding to U.S. Pat. No. 4,072,100), European Patent EP 0 167 196, European Patent EP 0 598 679 or WO 2004/016433. Examples of so-called numbering boxes to carry out the numbering process are disclosed for instance in German Patent DE 30 47 390, EP Patent EP 0 718 112, WO 2004/016433 or WO 2005/018945.
DE 26 34 221 (see also U.S. Pat. No. 4,072,100) discloses a numbering machine comprising at least two identical numbering boxes which are operated in a simultaneous manner. Means are provided to ensure that the serial numbers formed by the said at least two numbering boxes are the same. Each numbering box comprises a set of individual numbering wheels that can be actuated separately, i.e. one numbering wheel per digit of the serial number.
After the numbering process, the numbered substrates are commonly processed in a machine where piles of numbered substrates are firstly cut into bundles of individual security documents (each security document bearing a corresponding one of the numbered security prints). These bundles are then commonly banded and assembled to form packs of security documents. Substrates carrying banknotes, for instance, are usually processed by piles of hundred sheets each, each pile being cut into bundles of hundred banknotes which are then processed to form packs of ten bundles, each pack thus consisting of a total of one thousand individual banknotes. The processing of numbered substrates to form packs of bundles of security documents as summarized hereabove is for instance disclosed in German Patent DE 25 02 987 or European Patent EP 0 167 196.
It is sometimes desirable to process the numbered substrates into individual packs of security documents numbered in sequence. This task not only requires that the various security prints lying in the same position on the substrate within a given pile be numbered in sequence so that each bundle cut out of this pile includes consecutively-numbered security documents, but more critically requires that the cut bundles be collated in an adequate manner so as to build a complete series of security documents without interruption of the sequence of serial numbers throughout the assembled pack of bundles. This previously required a relative complex collecting system as disclosed in German Patent DE 25 02 987.
A solution to the problem of collating of security documents so as to form packs numbered in sequence has been proposed in European patent EP 0 598 679. Thanks to this numbering process, it is possible to assemble packs comprising ten bundles of hundred security documents each, with the serial numbers of the thousand security documents following each other in sequence. A disadvantage of the numbering process proposed in EP 0 598 679 however resides in the fact that the next series of thousand documents which receives the complete sequence of serial numbers that directly follows the serials numbers of a given series of thousand documents is derived from the following pile of sheets. In other words, should one desire to build a pack containing more than one thousand security documents numbered in sequence, this requires processing of at least two successive pile and accumulation of the corresponding bundles and packs until the desired number of security documents numbered in sequence is attained. As a matter of fact, with this prior art numbering process, M successive piles (i.e. M×100 substrates) is required in order to be able to build packs with M thousand security documents numbered in sequence.
An improved numbering process has thus been proposed in international application WO 2004/016433 which is incorporated herein by reference as regards the proposed numbering process. According to this numbering process, each of the security prints within a given pile (or layer) of 10N sheets are numbered in such a way that a single pile yields, after processing of the pile, k*n bundles of 10N security documents which are numbered in sequence (k and n respectively designating the number of columns and rows of security prints per substrate). With this improved numbering process, collating of the bundles is greatly simplified and does not require temporary storage of the bundles between successive piles, the bundles being simply collected and assembled one after the other. For example, a pile of hundred sheets carrying five columns and ten rows of security prints will yield a complete sequence of five thousand security documents numbered in sequence (or fifty bundles of hundred security documents) which can directly be assembled into packs without this requiring processing of a subsequent pile.
The numbering process disclosed in WO 2004/016433 can be summarized as follows: for substrates comprising a plurality of security prints which are arranged in k columns and n rows, successive runs (also referred to as “layers”) of 10N substrates each are numbered by providing each of the security prints with a serial number Serial#, the serial number Serial# being calculated with the formula:Serial#=Start#+α*[(r−1)*k*n*10N+((i−1)*n+(j−1))*10N+MOD(s−1;10N)],
where Start# is a starting number from which numbering starts, α is equal to −1 or +1 depending on whether numbering is carried out downwards or, respectively upwards, r identifies the run or layer of 10N successive substrates, i and j respectively identify the column and the row on the substrate where the security print to be numbered is located, and s is a number which identifies the substrate onto which the security print to be numbered is located.
In the above formula, function MOD(x; y) designates the so-called modulus function which returns the integer remainder of the division of y by x. In the above formula, function MOD(s−1; 10N) will thus return an integer number between 0 and 10N−1.
FIGS. 1A to 1H are tables which illustrate the numbering principle of WO 2004/016433 as applied to sheets carrying an array of five columns (k=5) and ten rows (n=10) of security prints, the sheets being numbered by successive runs, or layers, of hundred sheets (N=2). More precisely, FIGS. 1A to 1H respectively illustrate the serial numbers applied onto the security prints of the s=1st, 2nd, 100th, 101st, 102nd, 200th, 201st and 202nd sheets to be numbered. For the sake of illustration, it is assumed in this example that numbering is carried out downwards (α=−1) from a starting number Start# equal to “X,1,000,000”, symbol “X” designating one or more additional prefixes which can be manually set by the operator but which are not as such automatically actuated during the numbering process. In FIGS. 1A to 1H, the five columns are designated by letters A to E and are each attributed a corresponding column number i which ranges in this case from i=1 for column A to i=k=5 for column E. Similarly, each row is identified by a corresponding row number j which ranges in this case from j=1 to j=n=10. The position of each security print on the sheet may accordingly be designated by the combination of the letter designating the column number and of the row number where the security print is located.
Referring to FIGS. 1A to 1C, it will be understood that sheets 1, 2 and 100 belong to a same layer, namely the first layer composed of the first hundred sheets which are numbered. On the other hand, sheets 101, 102 and 200 which are illustrated in FIGS. 1D to 1F all belong to the second layer of hundred sheets (i.e. sheets 101 to 200), while sheets 201 and 202 which are illustrated in FIGS. 1G and 1H both belong to the third layer of hundred sheets (i.e. sheets 201 to 300). Each sheet that follows is numbered in a similar manner until the last sheet that can be numbered for the closed set of serial numbers in consideration, i.e. until the 1,000,000/50=20,000th sheet in this example.
FIGS. 2A to 2C illustrate on the other hand successive piles obtained from the piling of the first, second and third layers of hundred sheets after numbering has been performed. Each sheet within a given layer of hundred sheets will receive serial numbers in such a manner that, for each position, the following sheet in the same layer will bear a serial number that is decremented by one unit. Referring for instance to FIG. 2A which schematically represents the piling of the sheets of the first layer (i.e. a pile composed of sheets 1 to 100 disposed in sequence on top of the other), each position in the pile will include a series of hundred security prints that are numbered in sequence. More importantly, the serial number that directly follows the last serial number of one position will be the starting serial number of a subsequent position in the pile.
The path indicated by arrows in FIG. 2A which goes from position A1 to A10, continues from position B1 to B10, then from position C1 to C10, and so on until position E10, indicates the path to follow to ensure that the sequence of serial numbers remains uninterrupted. This path also represents the path that is followed when collating the various bundles to form packs of bundles numbered in sequence.
A complete sequence of serial numbers is present in each and every single layer of hundred documents. As illustrated in FIG. 2A, the first layer of hundred sheets (sheets 1 to 100) will cover a complete and uninterrupted sequence of k*n*10N=5,000 prints with serial numbers ranging from “X,0,995,001” to “X,1,000,000”. The layer that directly follows (i.e. the second layer comprising sheets 101 to 200) will, as illustrated in FIG. 2B, cover the following uninterrupted sequence of 5,000 prints with serial numbers ranging from “X,0,990,001” to “X,0,995,000”. The same of course applies for each subsequent layer, as for example illustrated in FIG. 2C which schematically shows a piled composed of the sheets of the third layer (sheets 201 to 300).
Thanks to the numbering principle of WO 2004/016433, each layer of 10N sheets with k*n security prints numbered in sequence will yield k*n bundles numbered in sequence and that can directly and easily be assembled to form packs of security documents without interruption of the sequence of serial numbers. A considerable advantage of this numbering principle reside in the fact that it allows to build packs of any desired size, since the numbering sequence remains uninterrupted not only within a given layer but also over a whole succession of layers. Collating of bundles in sequence can be achieved without any great difficulty at all as this process does not requires the temporary storage of bundles. The bundles of a given layer merely need to be processed in sequence along the path schematically illustrated in FIG. 2A.
A numbering box specifically designed to carry out the above numbering process is further disclosed in WO 2004/016433. This numbering box can be considered as an hybrid numbering box as it combines purely sequentially-actuated numbering wheels and independently-actuated numbering wheels. For instance, in case of numbering successive runs, or layers, of hundred substrates (N=2) with less than hundred security prints per substrate (k*n<100), the numbering wheels for the units and tenths of the serial number (i.e. digits 1 to N=2) are sequentially-actuated numbering wheels, which can be constructed as typical mechanical numbering wheels, and the numbering wheels for the hundredths and thousandths (i.e. digits 3 and 4) are independently-actuated numbering wheels. All subsequent numbering wheels (i.e. for digit 5, 6, 7 . . . )—except the prefix wheels—are again actuated in a sequential manner, mechanically, electromechanically or by any other appropriate means.
The individual actuation of the numbering wheels for the hundredths and thousandths is necessary in order to allow skipping to any appropriate number and ensure non-interruption of the numbering sequence, the amount of skipping depending on the substrate layout, in particular the number k*n of security prints per substrate. Referring for instance to FIGS. 1C and 1D, one can see that the serial numbers change from the 100th sheet to the 101st sheet by a determined amount. For numbering location A1 for example, the serial number must change from “X,0,999,901” on the 100th sheet to “X,0,995,000” on the 101st sheet, i.e. digit 4 of the serial number must skip from “9” to “5” while digit 3 must skip from “9” to “0”.
One disadvantage of the numbering box of WO 2004/016433 resides in the fact that its manufacturing costs are substantially higher than those of purely mechanical numbering boxes. On the other hand, typical mechanical numbering boxes wherein all numbering wheels bear the sequence of ten numerals “0” to “9” are not adapted to carry out the above numbering process as skipping of each numbering wheels can only occur in a purely sequential manner, preventing in particular the thousandths and hundredths numbering wheels from skipping to the appropriate numbers from one run to the next.
With some limitations as regards the substrate layout, it is however possible to design purely mechanical numbering boxes to carry out the numbering process of WO 2004/016433. International application WO 2005/018945, which is incorporated herein by reference in its entirety, for instance discloses numbering boxes which are adapted to carry out the numbering process of WO 2004/016433 on successive runs of hundred successive substrates each bearing a number k*n of security prints which is an integer multiple of ten. More precisely, the disclosed numbering boxes are specifically adapted to apply serial numbers composed of six digits (plus three additional prefixes) on substrates carrying twenty, forty or fifty security prints.
The numbering boxes of WO 2005/018945 are generally similar to conventional mechanical numbering boxes and still comprise individual ten-segment numbering wheels for each digit of the serial number which are actuated in a sequential manner. One of the particularities of these numbering boxes however resides in the fact that each box has a specific numbering configuration which is different for each numbering location. More precisely, each numbering box comprises a different and specific combination of numbering wheels for the hundredths (digit 3) and thousandths (digit 4), which only bear the required numerals for the corresponding numbering location. For the sake of simplicity, a detailed description of the numbering box configurations of WO 2005/018945 will not be repeated here.
One disadvantage of the numbering boxes of WO 2005/018945 may be seen in the fact that digits 4 and 3 composing the serial numbers are generated by two numbering wheels, as with conventional mechanical numbering wheels, an appropriate actuation mechanism being required in order to ensure that the adequate sequence for digits 3 and 4 is generated for each sheet. If one of these two numbering wheels experiences a skipping error, the correct sequence of digits will be lost. With the numbering boxes of WO 2005/018945, the corrective operation required to recover from this skipping error is made quite complex, particularly due to the fact that the same numerals are repeated several times on the hundredths and thousandths numbering wheels, which prevents the operators from readily understanding where the skipping error occurred.
Another disadvantage of the numbering boxes of WO 2005/018945 resides in the fact that different ratchet/cam profiles are required for the hundredths and thousandths numbering wheels depending on the numbering location, as for example illustrate in FIG. 2 of WO 2005/018945. This requirement negatively affects the manufacturing costs of the numbering boxes.